
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;

public class Maven {

    public static void main(String[] args) {
        List<String> list = new ArrayList<String>();
        Set<Integer> set = new HashSet<>();
        // 遍历
        for (String item : list) {
            System.out.println(item);
        }

        for (int i = 0; i < list.size(); i++) {
            System.out.println(list.get(i));
        }

        Iterator<String> it = list.iterator();
        while (it.hasNext()) {
            System.out.println(it.next());
        }

        // Map集合遍历其中的键值对  覆盖键值对
        Map<String, Integer> map = new TreeMap<String, Integer>();

        Set<String> set1 = map.keySet();
        for (String key : set1) {
            Integer value = map.get(key);
        }

        for (String key : map.keySet()) {
            Integer value = map.get(key);
        }
    }
}

/* 
 * import java.util.List
 * import java.util.Set
 * import java.util.Map
 * 
 * Aviator java表达式引擎
 * 
 * 
 * TreeSet  TreeMap
 * 
 * Maven 
 * 
 * equal为真 或 compareTo返回1 两个对象相等
 * 
 * 
 * 
 */
